Over the last few days, I've encountered this problem a couple of times. I'll log on to the HTF, scan the new messages for any of interest, and close the browser. When I come back a little later, none of the earlier messages are marked read--even when they haven't had any new posts. Today, it's gotten to where people are adding new posts and topics and they are showing up, but the old ones that haven't been replied to in hours are still showing as having new posts. I hope this makes sense.